Apparatus for muffling sounds



J. O. FISHER.

APPARATUS FOR MUFFLING SOUNDS.

APPLICATION FILED JAN- 23, 1918- avumufoz dfl'ozncma Patented June'l, 1920.

u |l| llllullllllllll' .I. O. FISHER.

APPARATUS FOR MUFFLING SOUNDS.

APPLICATION FILED JAN-23,1918.

1,341,976. Patented June 1, 1920.

2 SHEETS-SHEET 2.

O.Fisher, 6g

i said gases along some iine oi" JOSEPH O. FISHER, OF THE UNITED STATES NAVY.

APPARATUS FOR MUFFLING SOUNDS.

Application filed January 23, 1918.

To all whom it may concern:

Be it known that I, JOSEPH O. FISHER, a commander in the United States Navy and a citizen of the United States, residing at \Vashington, in the District of Columbia, have invented certain new and useful Improvements in Apparatus for Mufliing Sounds; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to an apparatus for mufliing sounds and has for its object to provide a means which will be more etticient in use than those heretofore proposed.

With this and other objects in view the invention consists in the novel combinations of parts constituting the apparatus, all as will be more fully hereinafter disclosed and particularly pointed out in the claims. I

Referring to the accompanylng drawings forming a part of this specification in which like numerals designate like parts in all the views a Figure 1 is a side elevational view partly in section of a muiiier made in accordance with this invention;

Fig. 2 is a View of a somewhat modified form of rotator or helically disposed element removed from the casing;

Fig. 3 is an end view of the parts shown in Fig. 2; I

Fig. 4 is a sectional view oi a casing partly broken away with a stili further modified form of rotator located therein;

Fig. 5 is a cross sectional View taken on the line 5-5 of Fig. 6, showing another modified form of helicalelement or rotator;

Fig. 6 is a sectional view taken on the line 6-6 of Fig. 5; and A Fig. 7 is a sectional view of a still rur ther' modified form of rotator;

As is well known, sounds caused by ex haust gases from engines and other appa: ratus are due to the intermittent discharge oi transiat into the a'trnospiiere, and the pn invention, morespeeificaily rert the motion of translation said gases into motion of rat destroy' their power of causn I I as will be clear from the construction new 10 i;=c'disclosed.

'1. may represent any suitable rhsrnarge or Specification of Letters Patent.

Patented June 1, 1920.

Serial No. 213,362.

exhaust pipe for the gases from an engine or other apparatus, 2 a connection between said pipe and the Inufiier casing 3, 4 a chamber in the discharge end of said casing, 5 any suitable discharge pipe joined to the chamber 4 and 6 any suitable cooling means.

The gases causing the sounds to be mufiied are received into a chamber 8 with which the inlet end of the casing 3 is provided, in the form of pulsations directed along the axis of said casing 3. From the chamber 8 the gases impinge on the surface 10 of the rotator or helical element 9, and they follow the convolutions of said element 9 until they reach the chamber 4:. In order that the said gases, after striking the surface 10, may not pass along the axis of the chamber 3 without receiving a rotational movement, I cause the blade of the rotator 9 to have a depth 11 which is sufiicient to at least reach the corn ter line of said casing, and it may be, if desired, extended beyond said center line. it thus results that the gases are compelled to traverse and cross the helical chamber formed by the convolutions of the rotator 9, and the casing 3 without motion in a straight linealong the aXis of said casing 3 until they haverotated through-an angle of say 270 or 360, or several complete revolutions.

After having rotated through some predetermined angle of a considerable dimension, I then permit the said gases to gradually escape in a straight line along the axis of the casing 3, by gradually cutting away the inner edge 17 or said helical element 9. This said cutting away of this said edge may begin at or about the point 13, illustrated in ig. 2, 0; at about the point 31, illustrated i.- Fig. i. The cutting away of the said inner edge 17 of the helical eienient produces a tapered orifice axially disposed with reference to the casing 3 which orifice n ler to more eneetuaiiy absorb via elation oi said or rally convert the said ,y

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gases d 18 in 2.

action reversed, and the pulsating gases al-' lowed to traverse .an expanding rotator, for the necessary obstruction to a pulsating action would, in that case, be taken away. Again, as this said obstruction, due to the compressed pitch of the rotator, begins to destroy said pulsating action of the gases, the cutaway portion 17 of said rotator permits the rotating gases to escape out of the apparatus in the form of an expanding cone, so that a maximum of noise is sup.- pressed, or prevented. Put into still other words, the gases having been thus given a substantial rotation around the axis of the chamber 3 without any opportunity at all to pulsate along the axis of said casing, the

energy of motion possessed by the entering gases will be found to have been very largely, if not entirely converted into centrifugal energy, although there will be a greater or less pulsating of the said gases along the direction of their helical path. The centrifugal force of the said rotating gases causesthe same to continue theirpulsating action at .a maximum distance from and around, rather than along the axis of the chamber, and therefore, they do not create the noise which would accompany said escape if they pulsated in the direction of the said axis. 7

By the time the gases have reached the chamber 4, illustrated in'dotted lines in Fig. 1, the inner edge 17 of the rotator has been so much cut away that substantially all the gases will rotate around the axis of said chamber 3, and by their own pressure, will pass out of said chamber into the atmosphere or into a discharge pipe such as 5, through an orifice of less diameter than the chamber and concentric .with the axis of the rotating gases, as the case may be. When so discharged, it is found in practice that very little, if any noise accompanies said gases.

The helix or rotator 9 is conveniently supported at each end by the spider like members 20 and 21,'which spiders are conveniently held together as by the Strips 22, and these supports may be inserted as a whole in the casing 3.

In the slightly modified form of rotator illustrated in Figs. 2 and 3, I have provided a foraminous covering, which fits'theintenor of its casing such as 3, and as it exerts a cushioning action and offers considerable resistance to the propagation of any material, but one or more layers of wire cloth is preferred. In the still further modified form of the invention shown in Fig. 4, the rotator is made up of separate sections 25 which are joined as at 2 6 to form the helix, and a similar foraminous covering 76 is also employed. The function of the covering 76 is substantially the same as that of the covering and need not be repeated.

This said construction shown in Fig. 4 avoids the difiiculty of properly shaping a single piece such as that lettered 9 in Fig. 2, and it renders it comparatively easy to locate the inner edge 17 of the individual sections 25 either directly in the axis of casing 3, or somewhat to one side of said axis, as may be desired by the'manufacturer. It is also comparatively easy to impart to a helix produced from sections 25 any desired decreased twist, as will be clear from the points lettered 27, 28, 29 and 30 in Fig. 4.

It is also easier in the manufacture of these helices to so cut away the inner edges 17 of said sections 27 to 30 as to regulate to a. nicety the shape and dimensions of the tapered discharge orifice 12 as is indicated by the dotted lines in Fig. 4.

In the still further modified form of rotator, shown in Fig. 5, the gases may enter the opening 35 of the pipe 34, while still pulsating in a straight line whereupon they will acquire a greater and greater angular or spiral motion in the same plane, so that this said angular motion coupled with its increase in angularity will serve to convert with quickness and efficiency the energy of motion into centrifugal energy after the gases have thus traveled in the direction of the arrows shown in 'Fig. 5, and have reached say the point 36 in said figure. The outlet 37 is given a helical form and the said gases are dischar ed into the chamber 38 tangentially to the circumference of the same, and the said gases continue to rotate, until their own pressure finally forces them to emer e through a discharge opening 39, similar in all respects to the opening 57 in Fig. 7, while the are still. rotating. Here again, although t e gases may possess a pulsating action along their line of motion, while rotating about an axis, yet at the same time, in practice on emergence through opening 57 they are found not to be accompanied by any substantial noises.

lutions into the cylindrical chamber 54,

around the circumference of which they likewise continue to rotate until finally their pressure will force them to pass through an opening 57 of less diameter than the path of rotation, and into the atmosphere, while they are still rotating around their axis of rotation.

Here again, it will be observed that the energy of motion of said gases has been converted into centrifugal energy of rotation, but this last mentioned motion, although still subject to pulsations, is found in practice to be incapable of causing the sounds when discharged to the atmosphere as above described.

A" foraminous covering member such as 7 5 or 76 is employed as a lining for the gas passages in. Figs. 5, 6 and 7, but it is not deemed necessary to illustrate it here.

It will now be clear that in all the forms of the invention:

First, that I start with an intermittent, or pulsating stream of gases having a motion in a given direction; that I convert a large part or substantially all the energy of motion. possessed by said gases into centrifugal energy while at the same time, 1 discharge the said gases in a rotating stream along the axis of rotation, and therefore, in a form which is not capable of producing the sounds which otherwise would occur.

Second, it will be observed that I line the gas passages with a foraminous covering which absorbs any sound waves and prevents the propagation of said sound waves along the gas. passages.

Since the gases enter the connection 2 in the form of a stream pulsating in a straight line, and since they are immediately, for a portion of their travel, forced by the helical members 9 or 25, to rotate around the longitudinal axis of the casing 3, it is evident that some of their original energy will be used up in acquiring this rotary motion. Therefore, said gases cannot after leaving said casing 3 pulsate in a straight line as violently as they could before entering the connection 2. created at the expense of the pulsating energy is made relatively large, it is obvious that the pulsations in a straight path will be relatively small, and that .the noise of the muiiler will be correspondingly reduced. This desirable result is enhanced by gradually opening a straight line path of escape for the rotating gases, as by cutting away the inner edges of the helices 9 or 25, and at If the rotational energy thus V the same time decreasing the pitch of said helices to partially obstruct any straight line pulsations that may still persist in the outer boundaries of said rotating gases.

It is therefore an especially important feature of the inventionthat my discharge orifices such as 12, 18, 39 and 57 are in a prolongation of the axis of rotation, for, while the gases were originally subject to pulsations due to wide variations in velocity their centrifugal force absorbs the energy of the gases of the highest velocity, and said orifices being free from all obstructions inthe paths of rotation, the gases of lowest velocity aregr'adually forced by their own pressure into said orifices, and out of the same without disturbing their continuous rotation. Accordingly, the tendency of said gases to take up an intermittent movement in the direction of the axis of the rotator is reduced to a minimum.

It is an equally important feature of my invention that the gas passages are lined with a foraminous roughened, or other sound absorbing material, which prevents the propagation of the sounds produced by the gases entering the mufiler.

It is obvious that those skilled in the art may vary the details of the process as well said gases while rotating the same to convert another portion of their energy into centrifugal energy and discharging said gases in an unobstructed. expanding rotating stream from said chamber, open to the atmosphere, substantially as described.

2. An apparatus for mufiling sounds comprising a chamber provided with a rotator adapted to impart to gases having a pulsating or intermittent motion a motion of an accelerated, rotation, and having a cone shaped orifice of less diameter than said path of rotation freely opening into the chamber and adapted to discharge said gases therefrom in an unobstructed rotating stream, substantially as described.

' 3. In an apparatus for mufiiin sounds the combination of casingprovi ed with an inlet and an outlet; and a helical member having a varying pitch located in said casing; said member near said outlet being cut away to provide an unobstructeddischarge opening from said chamber to said outlet, substantially as described.

4. In an apparatus for mufliing sounds the combination of a ,casing provided with receiving and discharge chambers, and with an inlet and an outlet respectively for said chambers; and a helically disposed member located in said casing between said chambers and cut away near its outlet end to provide an unobstructed passage to said discharge chamber, substantially as described.

5. In an apparatus for mufiling sounds the combination of a casing; an inlet for said casing; a receiving chamber in said cas ing into which said inlet leads; an outlet for said casing; a discharge chamber in said casing from which said outlet leads; and a helically disposed member having a decreasing pitch located between said chambers to form a continuous helical chamber in'said casing, the inner edge of said member being cut away near said discharge chamber to form an unobstructed connection between said helical and discharge chambers, substantially as described.

6. In an apparatus for mufliing sounds the combination of a casing; an inlet for said casing; a receiving chamber in said cas: ing into which said inlet leads; an outlet for said casing; a discharge chamber in said casing from which said outlet leads;- and a helically disposed member having a decreasing pitch located between said chambers to form a continuous helical chamber in said casing, the inner edge of said member fora portion of its length extending radially as far as the axis of said chamber, and for therest of its length being gradually cut away to form an unobstructed tapering connection between said helical and discharge chambers, substantially as described.

7 The process of muflling sounds due to intermittent discharges of gases into the at mosphere, which consists in converting the energy of motion of said intermittent discharges into an accelerated rotary motion while subjecting said gases to the mufiiing action of a foraminous substance and, discharging said gases in an unobstructed rotating and. expanding stream into the air, substantially as described.

8. An apparatus for mufiling sounds comprising a chamber having a rotator adapted to impart to gases having a pulsating or intermittent motion, an accelerated motion of rotation, and having a cone-shaped orifice of less diameter than said path of rotation freely opening into said chamber, said orifice adapted to discharge said gases from said chamber in an unobstructed expanding and rotating stream, and said chamber having foraminous lined passages, substantially as described.

9. In an apparatus for mufiiing sounds the combination of a casing provided with receiving and discharge chambers, and with an inlet and an outlet respectively for said chambers; a helically disposed member provided with a wire cloth covering, located in said-casing between said chambers and cut away near its outlet end to provide an unobstructed passage to said discharge chamber, substantially as described.

In testimony whereof I afiix my signature.

JOSEPH O. FISHER. 

